• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Polymers - ethene

Extracts from this document...

Introduction

The double bond in an alkene (like ethene) can be broken open and joined to other molecules. A molecule of ethene can be joined to another molecule of ethene. In the process, the second ethene molecule has its double bond broken, and this may be added to a third molecule of ethene, and so on. Many ethene molecules can be joined together to form a polymer. The polymer is called poly(ethene) because it is made from ethene. Poly(ethene) is commonly called polythene. Polythene is an ICI trademark for poly(ethene). Ethene put under pressure and heated with a catalyst will polymerise to form poly(ethene). Note that there are no double bonds in the polymer. Poly(ethene) is an alkane. It is a saturated hydrocarbon. A polymer is often written in the form A polymer which is formed from monomers added together where no substance (other than the polymer) ...read more.

Middle

When the polymer is heated the crystals will melt, the material will become very soft and can flow slowly like a thick liquid. In this state the polymer can fill a mould and be cast into a shape. When the polymer cools down, new crystals can form between the chains and the new shape is fixed. The same polymer can be reheated and remoulded. Such polymers are called thermosoftening (meaning that they go soft when you heat them). The picture below shows the tangled polymer chains which have lined up and crystallized in the pink region. Some polymers do not form crystals. They soften when heated and harden when cooled down again. When cold, they are not crystalline but glassy. These polymers are also called thermosoftening. ...read more.

Conclusion

Products from plant material (wood, paper, cotton etc.) are biodegradable. When buried, bacteria and fungi break them down into useful nutrients for further plant growth. Nature recycles its own products! Polymers produce toxic materials (poisons) when burnt, in addition to the expected products from combustion of a hydrocarbon which are carbon dioxide, water, carbon monoxide and carbon (soot). Those which contain chlorine (PVC for example) also produce hydrogen chloride on burning. Those which contain nitrogen (nylon for example) produce hydrogen cyanide. Polymers are a fire hazard. Many people die from the smoke of burning polymers in house fires, long before the fire reaches them. Burning polymers is not a good way of disposing of them. Solutions. More and more polymers are being recycled. This is not as cost effective as recycling metals, but we don't want to live amongst piles of (unrotting) plastic. Research into biodegradable polymers will increasingly provide useful replacements for the main polymers of today. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Resistant Materials section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Resistant Materials essays

  1. THE BENEFITS OF RECYCLING

    Glass Clear, amber and green glass from beverage bottles and food jars Window glass, light bulbs, crystal, ceramics, ovenware Rinse bottles and jars, remove lids, leave labels on. In some programs, separate by color. Paper Newspapers, corrugated paper, office paper, computer paper, magazines, catalogs, "junk" mail Waxed paper, coated paper, tissue paper Separate by type of paper.

  2. EFFECT OF MOISTURE ON THE MECHANICAL PROPERTIES OF NYLON

    Another dominant feature of Nylons is crystallinity. As with most crystalline polymers, the molecular chains are uncluttered by large substituent groups. They are flexible and regular in-group spacing and crystallize readily. As with acetals, this crystallinity is responsible for properties of wear resistance, chemical resistance, thermal resistance, and unfortunately, higher mold shrinkage.

  1. Supply Chain Management

    Two methods were prevalent during this period; 3C and DFT. 3C was developed in the early 1990s as an alternative to MRP with significantly less maintenance requirements. The 3C approach was essentially the same as DFT, with less emphasis placed on the bill of materials.

  2. Describe the layout and furniture of aTypical Athenian house.

    The women's quarters or Gynaikon were usually nearer the back of the house so that the man of the house could tell if she was trying to sneak out. In the women's quarters you would find a bedroom for them and a room for spinning and weaving materials and clothes.

  1. Six sigma methology for solving automotive engineering problems.

    Feasibility of using the values arrived for the design variables in the third phase are evaluated in the final phase called as the Engineering Judgement and Conclusion phase. Wherever, unrealistic values are arrived, closer realistic values are chosen and these are fed back into the regression equations to obtain the real responses.

  2. Chemistry polymers.

    These crystals can form links between the chains and hold the structure together. When the polymer is heated the crystals will melt, the material will become very soft and can flow slowly like a thick liquid. In this state the polymer can fill a mould and be cast into a shape.

  1. My aim of this experiment is to recognize which material is the greatest sound ...

    Therefore this experiment had progressed when I had changed using the CD player to the loudspeaker and sound generator. Moreover, I deem that when carrying out the experiment polystyrene would be the best insulator of sound, as when the atoms will not be able to penetrate due to the molecules

  2. The task has been set to make a hole punch (used to punch holes ...

    Many CAM programmes also enable the user to machine complex shapes. The products made are always identical, of a high quality and very accurate. If my hole punch was manufactured for batch production, each of my components would need to be able to be made using either jigs and fixtures or computer-aided machines.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work